1. Field of the Invention
This invention relates to an image forming apparatus having a plurality of LED heads and capable of forming stable images by equalizing light intensities of LED heads.
2. Description of the Related Art
A conventional image forming apparatus uses, as an image writing means, an LED head that has a line of LED elements along the main scanning direction. To make image recording faster and the service lives of LED elements longer, such an apparatus uses two or more LED heads and switches these heads by lines or by pages. If the light intensities of the LED elements are not equal, resulting images may have irregular densities.
Japanese Non-examined Patent Publication 2000-71508 discloses an image forming apparatus with a plurality of LED heads that are switched each time one image line is formed. This invention has an effect to eliminate unwanted white or black lines caused by different dot diameters of LED elements.
Although this prior art can eliminate unwanted white or black lines, the resulting images cannot be free from having density irregularities due to uneven light intensities of LED heads.
In other words, the prior art cannot suppress density irregularities in images recorded by the LED heads.